Do not use large dams for hydropower and dams and do not divert water from low dams

The first time I saw Wang Zhaoyin was in the special feature film “Hydropower Development and Geological Disaster Reduction” produced by the China Association of Hydroelectric Engineering and CCTV's original “Green Space” column group. An international sediment scholar, white shirt, wearing a straw hat, tanned skin and dark red, with his students, in Yunnan called a condolence river, do artificial ladder - deep pool energy dissipation experiments.

Soon, the Hydropower Association invited some news media to participate in the green forum on hydropower development and geological disaster reduction. As the guest speaker of the forum, the hydropower society first reviewed itself. He said that he originally thought that as a scholar, he should not be too close to the news media, but now the popular science work depends on the media, so he wants to correct this idea.

This year Wang Zhaoyin is 60 years old. During the last three years, he will go to the Qinghai-Tibet Plateau for field surveys almost twice a year. The last time it entered the Brahmaputra Grand Canyon in May this year, the road was steep, and the grasshopper bite was still on the way. From daylight to dusk, it took 28 km. The female doctoral student who was under him was bitten by a grasshopper. He dared not change his clothes, coupled with excessive physical exertion, was almost desperate and cried. This time in the field survey, although two cameras were lost at the rapids, the harvest was not small.

“At present, ecology is still shouting slogans and scrambled concepts. It is not willing to spend money. But as the society continues to advance, it will still be considered.”

Reporter: What is your inspiration for the study of erosion for building dams on the river?

Wang Zhaoyin: In fact, the root cause of erosion is the undercutting of rivers. The river cuts the source and transmits it from the big river to the tributary and then from the tributary to the valley. Dam construction, especially the construction of cascade dams, and control of lower cuts in rivers, can also increase resistance and reduce energy, making the river stable, less erosion, and better ecology.

Our study found that more than 95% of the 36 species of freshwater fish in the world prefer flow rates below 2 m/s, and some fish spawning require a higher flow rate. Most fish prefer a flow rate of 0.3-1.5 m/s. More than 2 meters are injured. Most fishes over 3 meters per second cannot survive. Exceeding 4 meters per second. After the dam was built, the flow rate was reduced, and the river became a habitat for rivers and lakes, and more species were adapted.

Undoubtedly, dams will have an impact on ecology. In general, fish are spawned in the upper reaches of the river and grow up in the lower reaches. In order to swim, building a dam will cause the fish to be blocked. Then there is the change in water temperature, especially the large dams, which has a great ecological impact. The lower cascade dams cause less ecological pressure and more benefits.

Reporter: With regard to the protection of fish, we are now doing some work. Compared with foreign countries, how much have we done?

Wang Zhaoyin: The Columbia River in the United States is a very important ecological river. Seven dams have been built on the river. How the fish pass the dam is a very important issue. One of the problems with fish over dams is how the spawning brooders go up the dam. One is how the small fish generated after spawning passes down the dam. I have visited the Canaveral Dam, and more than 1 million brooders cross the dam each year, mainly salmon. The Americans build fish ladders along the side of a dam with a height of more than 100 meters. They consist of more than 200 chambers, each of which reduces its head by more than half a meter. The water passes through the chambers from above to below, and the water comes in from the window. The flow suddenly opens and then narrows from the other window into the next chamber. This consumes water energy, controls the flow rate, and is high only when passing through the window. The brooders went up from the dam to the dam and entered a small room. They could take a rest in the house, and then sent a force through the window to the next level room. I have seen another kind of fish ladder in Europe. I have planted numerous plastic rods into shrubs. The clumps and bushes cause high-frequency vibrations as the water passes through. The energy consumption causes the flow rate to slow down. Small fish can pass through the gap and the big fish can Between the two bushes past.

The key to the success of the fish ladder is how to attract fish into the fish ladder. Many designs of fish ladders are unsuccessful because fish do not enter and fish ladders are built. The water is used to identify the upstream and downstream directions. The water velocity is too low and it is not recognized. The speed is too high to swim. This requires biological research. The fish ladder was once one of the hot topics in the field of water conservancy. Now the design is more experienced. The second question is how the growing fish go. The mortality rate of fish over water turbines is around 20%. There are 7 dams on the Columbia River, and most of the 7 fish dams have died. This requires the training of small fish and tells them that it is a turbine that cannot pass. It is a fish pass. Therefore, by doing some water flow regulation in foreign countries and blocking it in front of the turbine, it had to come back and it would be able to pass through the fish pass. The fish is very awkward. You teach it part of it and everything else will. This I just said is also on the Columbia River in the United States. Now they are studying the problem of the hydraulics of fish. They are implanting chips on the body of the fish and sending signals. A thing is a hundred dollars, and the cost is still very high.

Reporter: In comparison with that, our country is lagging behind in doing this.

Wang Zhaoyin: Yes. There are two reasons. One is that our development has not yet reached this stage. At present, the ecology is still shouting slogans speculation, spending money is not willing. To do fish ladders and fish lanes, our country will not be able to talk about it for the time being. It will cost money. Scientific research is also relatively backward, because scientific research is driven by production. If the Three Gorges Dam does not build a fish ladder, who will pay for it to study it? Another reason is that there are not many fish that have particularly economic value in China. The four major populations of the Yangtze River (herbtail grass carp carp) also have spawning sites below the Gezhouba Dam, and the Three Gorges Project did not consider the fish ladder fishway. However, I think that with the continuous progress of society in the future, ancillary facilities that will reduce the ecological impact of the dam will still be considered.

“There are many problems caused by the large dams, such as barriers to fish migration, water temperature stratification, and the destruction of rivers and lakes.”

Reporter: Why did you say you want to avoid the high dam database?

Wang Zhaoyin: There are many problems caused by the large dams. From an ecological point of view, we should avoid a single large dam. A large number of silt deposits in the high dam area and significant downstream scour. High dams cut off the migratory route and have a great impact on migratory species. The high dam bank significantly changed the state of water flow, and it was impossible to lay eggs for those organisms that rely on natural flood level changes as life signals for spawning. For example, some fish produce floating eggs, which require high water flow rates and can float on the water. Brooders spawned to watch the flood rise, and the water level rose to increase spawning speed. After the dam was built, the floodwaters were reduced, and the fish did not know when to lay eggs. Then there is the problem of water temperature. Temperature stratification usually occurs in large reservoirs. The generation holes venting the lower layers of hypoxic and low-temperature water can cause some creatures to not spawn or spawn in time. There is also the destruction of rivers and lakes. For example, in the Three Gorges Reservoir, the downstream erosion led to deep riverbeds, lower water levels, and flood waters could not reach the Dongting Lake, resulting in a decrease in connectivity between rivers and lakes.

Reporter: What are the consequences of reducing the connectivity of rivers and lakes?

Wang Zhaoyin: The connection between rivers and lakes is very important for some creatures. Why is the four-major fish reduced by 90%? Of course, this is not exactly what happened in the Three Gorges, but the destruction of rivers and lakes is a major problem, which has caused the fragmentation of habitats. The original ecology of the entire Yangtze River basin was very good. It benefited from this river-lake connectivity system. Many creatures spawn in the river and grow up in the lake. In different stages of life, they need to find a suitable living environment. For example, some need flowing water, pebble beds, some have plankton, and some have slow flow and adequate nutrients. The original Dongting Lake and Poyang Lake were connected with the Yangtze River, and the fish production was very high. The relatively large impact of the Three Gorges is the connectivity with the Dongting Lake.

The decline in the connectivity between rivers and lakes is not the cause of the Three Gorges. Before the Three Gorges Dam, thousands of large and small lakes were basically artificially disconnected from the Yangtze River. The first reason is flood control. The Yangtze River rises in water, and the height of the river embankment blocks it. If it is connected, the height of the lake embankment must be raised. The cost is much higher. The flood control embankment in the middle and lower reaches of the Yangtze River is over 3,000 kilometers long, and the lake embankment is more than 30,000 kilometers. The second reason is fish farming. Honghu used a large gate and opened it manually. It did not follow the rules of biological migration. It was impossible to connect the boat when it was on the boat. It was impossible for the fish to go to the river. It depends on whether or not the person is allowed to leave. It also does not know the law of people's release. Therefore, many fish that need to rely on rivers and lakes disappeared.

The four major fish are the main species of the Yangtze River fishery. There were a total of 27 spawning sites for the four home fishes, 11 under Gezhouba Dam and 16 above Gezhouba Dam. After Gezhou Dam in 1980, basically it was impossible to go upwards, but spawned below, causing a drop in production. After the impoundment of the Three Gorges Dam, the flow of flood peaks was changed and the fry output fell by 97%. According to the Three Gorges Project Eco-environment Monitoring Bulletin, the amount of fry in the four major fishes in 2009 was less than 2% before the Three Gorges application. This year's Three Gorges project took into account the ecological requirements for proliferation and release, and the release of spawn signals to the four major fishes under the dam may reduce the impact of the dam to some extent.

Reporter: Is there a connection between the drought in the middle and lower reaches of the Yangtze River and the rivers and lakes?

Wang Zhaoyin: This still needs to be studied. I think the impact on the climate cannot be directly derived from logical reasoning. The disconnection of most rivers and lakes from the Yangtze River is not caused by the Three Gorges but is caused by human activities. For the prevention of floods and fish farming, most of them have been separated long ago. Only Dongting Lake and Poyang Lake maintain a certain degree of connectivity. However, after the completion of the Three Gorges Project, the connectivity was significantly reduced, and the river bed was reduced by more than 10 meters. It is now impossible for ordinary floodwaters to enter the Dongting Lake. However, the impact on the climate must be further studied. There is a dam on the tributary of the Amazon River, which has encountered two major droughts in a hundred years after it was completed within 10 years. As for the Three Gorges caused severe drought in Chongqing, there are different views, but there is no sufficient evidence to support it. This requires meteorological experts to conduct research based on data from analysis of meteorological observations, including comparisons with pre-damage data. If there is no comparison, it is not easy to draw conclusions. Someone took this out and rushed to approve the Three Gorges, and there was a bit of hype in it. However, the downstream erosion is very serious. This problem exists.

"Diversionary power generation is to kill chickens and take eggs. Even if 5% of the water is maintained, fish cannot survive."

Reporter: What about water diversion?

Wang Zhaoyin: As for water diversion-type power generation, this method is used on many rivers in the southwest because of its low cost. Build small dams or no dams on the river, transport river water through straight culverts and pipelines to the downstream to increase hydroelectricity. There is no water or no flow between the small dam and the power station, and none of the creatures can survive. This impact on ecology is deadly and should be avoided. As a compensation measure, the use of swarms to maintain a certain water depth (although there is no flow of water) can reduce this deadly effect.

Reporter: Diversionary power generation is generally a quotation. It is impossible for the river's creatures to concentrate on this section to survive.

Wang Zhaoyin: River water ecology is a complete system, each part is connected to each other. Destruction of this integrity is a great destruction. There is no water between the dam and the power station. The river in the middle will dry up. Even if you maintain 5% of the water, the fish will not survive. This method is equivalent to killing chickens. I do not think this is a good idea. Do not divert water to generate electricity, and do not have a single high dam. Medium-sized dams are the best.

Reporter: According to your research, what are the main impacts of the rising of the Qinghai-Tibet Plateau on Sanjiang?

Wang Zhaoyin: The first one is of course undercutting, which causes geological instability and is prone to collapse and landslides. At the same time, the energy of the water flow is also accumulating, and the greater the height difference, the greater the energy. I agree with Zhang Boting’s opinion that hydropower development on the edge of the Qinghai-Tibet Plateau’s rivers, including the Jinsha River, Minjiang River, and Nu River, is actually beneficial. Investment funds for hydropower development can manage disasters. If hydropower development also emphasizes energy dissipation and disaster reduction, it will be beneficial to rivers in southwest China. Although it has a certain impact on the ecological impact, it also creates certain conditions for many ecological species. It should be said that the advantages outweigh the disadvantages. Some people will think that as long as the artificial changes are definitely not good for the ecology, let alone generating electricity. This statement is correct in many cases abroad, but it is incorrect for the river around the Tibetan Plateau. Constructing dams on these rivers (medium-height dams not exceeding 100 meters in diameter) may not always be a bad thing for ecology. Although it may have a certain impact on the original river species, the new river-lake connectivity system created can create important habitats for many species. If the use of dams remains stable over a long period of time, the biological density and biodiversity of the species may not only decrease but also increase. These three rivers have high flow rates at the edge of the plateau. There are not many important species and the number of organisms is very small. Of course, our investigation is not detailed enough, but so far no species has been found to be unique, and once it has become extinct, it is gone. If that is the case, we must reconsider whether we are developing.